Vapor chamber

ABSTRACT

This disclosure relates to a vapor chamber configured to accommodate a cooling fluid. The vapor chamber includes a first cover, a second cover, a first capillary structure, and a second capillary structure. The second cover and the first cover are attached to each other to form a chamber therebetween. The chamber is configured to accommodate the cooling fluid. The first capillary structure is located in the chamber and stacked on the first cover. The second capillary structure is located in the chamber and stacked on the first capillary structure. The second capillary structure is different from the first capillary structure. A projection of the second capillary structure onto the first cover is smaller than a projection of the first capillary structure onto the first cover.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional patent application of U.S. patent application No. 16/899,495, filed on Jun. 11, 2020 and entitled “VAPOR CHAMBER”, which is a non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 201911340537.1 filed in China, P.R.C. on Dec. 23, 2019, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a vapor chamber, more particularly to a vapor chamber having multiple forms of capillary structures.

BACKGROUND

A vapor chamber and a heat pipe can be applied to dissipate heat. Thermal conduction of a heat pipe occurs in one dimension while thermal conduction of a vapor chamber occurs in two dimensions. Therefore, the vapor chamber is more effective in heat dissipation. Generally, the vapor chamber includes a chamber body and a capillary structure, the chamber body has a chamber for accommodating cooling fluid, and the capillary structure is distributed in the chamber. The chamber body contains an evaporation area and a condensation area. The cooling fluid absorbs heat and is vaporized in the evaporation area. And the vaporized cooling fluid is condensed in the condensation area and then returned to the evaporation area via the capillary structure to form a circulation.

However, with the increasing demand for lightweight and small electronic products, some vapor chambers are in an irregular shape to avoid structural interference with nearby electrical components. This shape of vapor chamber inevitably has a narrow portion, where the narrow portion has a small cross-section for the distribution of the capillary structure so that the cooling fluid is often stuck in this area and unable to complete the circulation, especially when the vapor chamber is placed vertically.

SUMMARY

The present disclosure provides a vapor chamber that has an improved ability to circulate cooling fluid.

According to one aspect of the present disclosure, a vapor chamber is configured to accommodate a cooling fluid. The vapor chamber includes a first cover, a second cover, a first capillary structure, and a second capillary structure. The second cover and the first cover are attached to each other to form a chamber therebetween. The chamber is configured to accommodate the cooling fluid. The first capillary structure is located in the chamber and stacked on the first cover. The second capillary structure is located in the chamber and stacked on the first capillary structure. The second capillary structure is different from the first capillary structure, and a projection of the second capillary structure onto the first cover is smaller than a projection of the first capillary structure onto the first cover.

According to another aspect of the present disclosure, a vapor chamber is configured to accommodate a cooling fluid. The vapor chamber includes a first cover, a second cover, a first capillary structure, and a second capillary structure. The second cover and the first cover are attached to each other to form a chamber therebetween. The chamber is configured to accommodate the cooling fluid. The first capillary structure is located in the chamber and stacked on the first cover. The second capillary structure is located in the chamber and stacked on the first capillary structure. The second capillary structure has a capability of transmitting the cooling fluid stronger than that of the first capillary structure.

According to the vapor chamber discussed above, when the vapor chamber is placed vertically and the evaporation area is located higher than the condensation area, or when the evaporation area and the condensation area have a relative long distance inbetween, the condensed cooling fluid in the condensation area still can be transmitted back to the evaporation area with the help of the second capillary structure and the first capillary structure to complete the circulation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only and thus are not intending to limit the present disclosure and wherein:

FIG. 1 is a perspective view of a vapor chamber according to a first embodiment of the present disclosure;

FIG. 2 is another perspective view of the vapor chamber in FIG. 1 ;

FIG. 3 is a plan view showing that the vapor chamber in FIG. 1 without the second cover;

FIG. 4 is a cross-sectional view of the vapor chamber in FIG. 1 ;

FIG. 5 is a cross-sectional view of a vapor chamber according to a second embodiment of the present disclosure;

FIG. 6 is a plan view showing that a vapor chamber without a second cover according to a third embodiment of the present disclosure;

FIG. 7 is a plan view showing that a vapor chamber without a second cover according to a fourth embodiment of the present disclosure;

FIG. 8 is a plan view showing that a vapor chamber without a second cover according to a fifth embodiment of the present disclosure;

FIG. 9 is a plan view showing that a vapor chamber without a second cover according to a sixth embodiment of the present disclosure;

FIG. 10 is a plan view showing that a vapor chamber without a second cover according to a seventh embodiment of the present disclosure;

FIG. 11 is a plan view showing that a vapor chamber without a second cover according to an eighth embodiment of the present disclosure;

FIG. 12 is a plan view showing that a vapor chamber without a second cover according to a ninth embodiment of the present disclosure;

FIG. 13 is a plan view showing that a vapor chamber without a second cover according to a tenth embodiment of the present disclosure;

FIG. 14 is a plan view showing that a vapor chamber without a second cover according to an eleventh embodiment of the present disclosure; and

FIG. 15 is a plan view showing that a vapor chamber without a second cover according to a twelfth embodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

Please refer to FIG. 1 to FIG. 4 , wherein FIG. 1 is a perspective view of a vapor chamber according to a first embodiment of the present disclosure, FIG. 2 is another perspective view of the vapor chamber in FIG. 1 , FIG. 3 is a plan view showing that the vapor chamber in FIG. 1 without the second cover, and FIG. 4 is a cross-sectional view of the vapor chamber in FIG. 1 .

This embodiment provides a vapor chamber 10 configured to accommodate a cooling fluid (not shown). The vapor chamber 10 includes a first cover 100, a second cover 200, a first capillary structure 300, and a second capillary structure 400.

The first cover 100 and the second cover 200 are made of, for example, oxygen-free copper, silicon-containing copper alloy, or phosphorous copper alloy. The second cover 200 and the first cover 100 are attached to each other to form a chamber S therebetween. The cooling fluid is accommodated in the chamber S.

In this embodiment, the vapor chamber 10 may further include a plurality of supporting posts 270. The supporting posts 270 are in physical contact with the first cover 100 and the second cover 200. The supporting posts 270 are able to maintain the gap between the first cover 100 and the second cover 200 and to strengthen the structural strength of the vapor chamber 10.

In this embodiment, the vapor chamber 10 further includes a hollow part 500. The hollow part 500 is, for example, a through hole formed on the first cover 100 and the second cover 200, but the hollow part 500 does not affect the airtightness of the chamber S. Specifically, there are an outer seal part 250 and an inner seal part 260 provided along the contours of the first cover 100 and the second cover 200, where the outer seal part 250 goes along the outer edges of the first cover 100 and the second cover 200, and the inner seal part 260 goes along the contour of the hollow part 500. Note that the contours of the outer seal part 250 and the inner seal part 260 may be in irregular shapes to avoid structural interference with nearby electrical components (not shown), but the present disclosure is not limited thereto. In some embodiments, the outer seal part and the inner seal part in irregular shapes may have a zigzag structure, a curved structure or an uneven structure. In some other embodiments, the contours of the outer seal part and the inner seal part may be in a regular shape, such as rectangle, oval, or circle.

In this embodiment, the chamber S has an evaporation area A1 and a condensation area A2. As shown, due to the existence of the hollow part 500 and the irregular shape, the condensation area A2 is narrower than the evaporation area A1 (W2 is smaller than W1).

In this embodiment, the first cover 100 has a contact surface 110 corresponding to the evaporation area A1. The contact surface 110 is configured to be in thermal contact with a heat source (not shown).

The first capillary structure 300 and the second capillary structure 400 are located in the chamber S. The first capillary structure 300 is stacked on the first cover 100, and the second capillary structure 400 is stacked on the first capillary structure 300. The second capillary structure 400 is different from the first capillary structure 300. An orthogonal projection of the second capillary structure 400 onto the first cover 100 is smaller than that of the first capillary structure 300 onto the first cover 100. The orthogonal projection is also known as the orthographic projection. Note that the orthogonal projections are projected along the same direction perpendicular to the surface of the first cover 100. Note that the orthogonal projection is for the purpose of description and is not intended to limit the present disclosure. In some embodiments, the relationship between the first capillary structure 300 and the second capillary structure 400 can be described using their oblique projections, where the oblique projections are projected along the same direction which is at an acute or obtuse angle to the surface of the first cover 100.

In this embodiment, the first capillary structure 300 is made of, for example, a metal mesh, and the second capillary structure 400 is made from, for example, sintered powder, however, the present disclosure is not limited thereto. The first capillary structure 300 and the second capillary structure 400 may be made of different materials. In one embodiment, the first capillary structure 300 is made of gold, and the second capillary structure 400 is made of copper. In another embodiment, the first capillary structure 300 and the second capillary structure 400 are made of different alloys. In addition, the first capillary structure 300 and the second capillary structure 400 may be different in the form of capillary. In one embodiment, the first capillary structure 300 may be in one form of having groove structure, mesh structure, fiber structure, or sintered powder structure, and the second capillary structure 400 may be in another form of having groove structure, mesh structure, fiber structure, or sintered powder structure. The first capillary structure 300 and the second capillary structure 400 may be in the same type but have different pore sizes; in one embodiment, the first capillary structure 300 and the second capillary structure 400 are in the form having mesh structure, but the pores of the first capillary structure 300 are larger than that of the second capillary structure 400.

In this embodiment, as shown, the first capillary structure 300 is distributed throughout the chamber S, and the second capillary structure 400 is distributed in part of the chamber S. One side of the second capillary structure 400 is located in the condensation area A2 and another side of the second capillary structure 400 extends towards the evaporation area A1. However, the distributions of the first capillary structure 300 and the second capillary structure 400 in the chamber S are not restricted; in some embodiments, the first capillary structure may also be merely distributed in part of the chamber S as long as the orthogonal projection of the second capillary structure onto the first cover is smaller than that of the first capillary structure onto the first cover.

In this embodiment, the orthogonal projection of the second capillary structure 400 onto the first cover 100 does not overlap with the contact surface 110, where the range of the contact surface 110 on the first cover 100 is illustrated as the area C. Specifically, the second capillary structure 400 is in a ring-shape and has a first curved section 410, a second curved section 420, and two extension sections 430. The first curved section 410 and the second curved section 420 are located opposite to each other. The first curved section 410 is located in the condensation area A2, and at least part of the second curved section 420 is located in the evaporation area A1. An orthogonal projection of the second curved section 420 onto the first cover 100 is located out of and substantially located next to the area C of the contact surface 110 of the first cover 100. The extension sections 430 are located opposite to each other. The extension sections 430 are respectively located between and connected to the first curved section 410 and the second curved section 420. In such an arrangement, the cooling fluid in the condensation area A2 will be transmitted to a place near the contact surface 110 in the evaporation area A1 via the second capillary structure 400 and then be transmitted to the contact surface 110 in the evaporation area A1 via the first capillary structure 300.

In this embodiment, the second capillary structure 400 is in a ring-shape and located at the periphery of the hollow part 500. In other words, the second capillary structure 400 surrounds the hollow part 500. In addition, the second capillary structure 400 is located close to an attachment surface 260′ of the inner seal part 260 but is located away from an attachment surface 250′ of the outer seal part 250. As shown, the distance between the second capillary structure 400 and the attachment surface 260′ is smaller than the distance between the second capillary structure 400 and the attachment surface 250′. Such an arrangement of the second capillary structure 400 in the chamber S makes the chamber S has a large available room for the vaporized cooling fluid to flow, ensuring the flowing of the cooling fluid in the chamber S.

In addition, as shown in FIG. 4 , in this embodiment, the second capillary structure 400 is spaced apart from the second cover 200. That is, the second capillary structure 400 is not in directly thermally conductive contact with the second cover 200.

When the vapor chamber 10 is placed vertically and the evaporation area A1 is located higher than the condensation area A2, or when the evaporation area A1 and the condensation area A2 have a relative long distance inbetween, the condensed cooling fluid in the condensation area A2 still can be transmitted back to the evaporation area A1 with the help of the second capillary structure 400 and the first capillary structure 300 to complete the circulation

In this embodiment, the vapor chamber 10 may be manufactured by the following steps: firstly, the first capillary structure 300 is sintered on the first cover 100; then, the second capillary structure 400 being pre-sintered is stacked on the first capillary structure 300; then, the first cover 100 and the second cover 200 are soldered to each other. Note that the second capillary structure 400 is not necessary to be pre-sintered; in some embodiments, the second capillary structure may be produced by placing capillary material on the first capillary structure and sintering it.

In the above embodiment, the second capillary structure 400 is spaced apart from the second cover 200, but the present disclosure is not limited thereto. Please refer to FIG. 5 , which is a cross-sectional view of a vapor chamber according to a second embodiment of the present disclosure. Note that only the main differences between the following embodiments and the previous embodiment will be described hereinafter. And the same numbers refer to the same or similar features. In this embodiment, the second capillary structure 400 a is in thermal contact with the second cover 200 so as to enhance the heat exchange efficiency.

In the above embodiments, the second capillary structure 400 is located close to the attachment surface 260′ of the inner seal part 260. However, the present disclosure is not limited thereto. Please refer to FIG. 6 , which is a plan view showing that a vapor chamber without a second cover according to a third embodiment of the present disclosure. In this embodiment, the second capillary structure 400 b is located close to the attachment surface 250′ of the outer seal part 250 (shown in FIG. 1 ). Such an arrangement of the second capillary structure 400 b in the chamber S makes the chamber S has a large available room for the vaporized cooling fluid to flow, ensuring the flowing of the cooling fluid in the chamber S.

In the above embodiments, the orthogonal projection of the second capillary structure 400 onto the first cover 100 is located out of the area C of the contact surface 110 of the first cover 100. However, the present disclosure is not limited thereto. Please refer to FIG. 7 , which is a plan view showing that a vapor chamber without a second cover according to a fourth embodiment of the present disclosure. In this embedment, part of the orthogonal projection of the second capillary structure 400 c onto the first cover 100 is located in the area C of the contact surface 110 of the first cover 100. Specifically, the second capillary structure 400 c is in a ring-shape and has a first curved section 410 c, a second curved section 420 c, two extension sections 430 c, and a bridge section 440 c. The first curved section 410 c and the second curved section 420 c are located opposite to each other. The first curved section 410 c is located in the condensation area A2, and at least part of the second curved section 420 c is located in the evaporation area A1. An orthogonal projection of the second curved section 420 c onto the first cover 100 is located out of the area C of the contact surface 110 of the first cover 100. The extension sections 430 c are located opposite to each other. The extension sections 430 c are respectively located between and connected to the first curved section 410 c and the second curved section 420 c. One end of the bridge section 440 c is connected to the second curved section 420 c, and an orthogonal projection of another end of the bridge section 440 c onto the first cover 100 is located in the area C of the contact surface 110 of the first cover 100. In such an arrangement, the cooling fluid in the condensation area A2 will be transmitted to the contact surface 110 in the evaporation area A1 via the second capillary structure 400 c.

In the above embodiments, the second capillary structure is in a ring-shape. However, the present disclosure is not limited thereto. Please refer to FIG. 8 and FIG. 9 , wherein FIG. 8 is a plan view showing that a vapor chamber without a second cover according to a fifth embodiment of the present disclosure, and FIG. 9 is a plan view showing that a vapor chamber without a second cover according to a sixth embodiment of the present disclosure. As shown in FIG. 8 , in this embodiment, the second capillary structure 400 d is in a U-shape and has a curved section 460 d and two extension sections 470 d. The curved section 460 d is located in the condensation area A2. The extension sections 470 d are located opposite to each other. The extension sections 470 d are respectively connected to two opposite ends of the curved section 460 d and extend towards the evaporation area A1. An orthogonal projection of an end of each of the extension sections 470 d located away from the curved section 460 d onto the first cover 100 is located in the area C of the contact surface 110 of the first cover 100. As shown in FIG. 9 , the second capillary structure 400 e is in a U-shape and has a curved section 460 e and two extension sections 470 e. The curved section 460 e is located in the condensation area A2. The extension sections 470 e are located opposite to each other. The extension sections 470 e are respectively connected to two opposite ends of the curved section 460 e and extend towards the evaporation area A1. An orthogonal projection of an end of each of the extension sections 470 e located away from the curved section 460 e onto the first cover 100 is located out of and substantially located next to the area C of the contact surface 110 of the first cover 100.

In the above embodiments, the vapor chamber 10 has a hollow part 500 (shown in FIG. 1 ). However, the present disclosure is not limited thereto. Please refer to FIG. 10 , which is a plan view showing that a vapor chamber without a second cover according to a seventh embodiment of the present disclosure. In this embodiment, the orthogonal projection of the second capillary structure 400 f onto the first cover 100 f is located out of and substantially located next to the area C of the contact surface 110 of the first cover 100 f. Specifically, the second capillary structure 400 f is in a ring-shape and has a first curved section 410 f, a second curved section 420 f, and two extension sections 430 f. The first curved section 410 f and the second curved section 420 f are located opposite to each other. The first curved section 410 f is located in the condensation area A2, and the second curved section 420 f is located next to the evaporation area A1. An orthogonal projection of the second curved section 420 f onto the first cover 100 f is located out of and substantially located next to the area C of the contact surface 110 of the first cover 100 f. The extension sections 430 f are located opposite to each other. The extension sections 430 f are respectively located between and connected to the first curved section 410 f and the second curved section 420 f. In such an arrangement, the cooling fluid in the condensation area A2 will be transmitted to a place near the contact surface 110 in the evaporation area A1 via the second capillary structure 400 f and then be transmitted to the contact surface 110 in the evaporation area A1 via the first capillary structure 300.

Please refer to FIG. 11 , which is a plan view showing that a vapor chamber without a second cover according to an eighth embodiment of the present disclosure.

In this embodiment, the second capillary structure 400 g is located close to the attachment surface 250′ of the outer seal part 250 (shown in FIG. 1 ). Such an arrangement of the second capillary structure 400 g in the chamber S makes the chamber S has a large available room for the vaporized cooling fluid to flow, ensuring the flowing of the cooling fluid in the chamber S.

Please refer to FIG. 12 , which is a plan view showing that a vapor chamber without a second cover according to a ninth embodiment of the present disclosure.

In this embodiment, part of the orthogonal projection of the second capillary structure 400 h onto the first cover 100 h is located in the area C of the contact surface 110 of the first cover 100 h. Specifically, the second capillary structure 400 h is in a ring-shape and has a first curved section 410 h, a second curved section 420 h, two extension sections 430 h, and a bridge section 440 h. The first curved section 410 h and the second curved section 420 h are located opposite to each other. The first curved section 410 h is located in the condensation area A2, and the second curved section 420 h is located next to the evaporation area A1. An orthogonal projection of the second curved section 420 h onto the first cover 100 h is located out of the area C of the contact surface 110 of the first cover 100 h. The extension sections 430 h are located opposite to each other. The extension sections 430 h are respectively located between and connected to the first curved section 410 h and the second curved section 420 h. One end of the bridge section 440 h is connected to the second curved section 420 h, and an orthogonal projection of another end of the bridge section 440 h onto the first cover 100 h is located in the area C of the contact surface 110 of the first cover 100 h. In such an arrangement, the cooling fluid in the condensation area A2 will be transmitted to the contact surface 110 in the evaporation area A1 via the second capillary structure 400 h.

Please refer to FIG. 13 and FIG. 14 , wherein FIG. 13 is a plan view showing that a vapor chamber without a second cover according to a tenth embodiment of the present disclosure, and FIG. 14 is a plan view showing that a vapor chamber without a second cover according to an eleventh embodiment of the present disclosure.

As shown in FIG. 13 , in this embodiment, the second capillary structure 400 i is in a U-shape and has a curved section 460 i and two extension sections 470 i. The curved section 460 i is located in the condensation area A2. The extension sections 470 i are located opposite to each other. The extension sections 470 i are respectively connected to two opposite ends of the curved section 460 i and extend towards the evaporation area A1. An orthogonal projection of an end of each of the extension sections 470 i located away from the curved section 460 i onto the first cover 100 i is located in the area C of the contact surface 110 of the first cover 100 i. As shown in FIG. 14 , the second capillary structure 400 j is in a U-shape and has a curved section 460 j and two extension sections 470 j. The curved section 460 j is located in the condensation area A2. The extension sections 470 j are located opposite to each other. The extension sections 470 j are respectively connected to two opposite ends of the curved section 460 j and extend towards the evaporation area A1. An orthogonal projection of an end of each of the extension sections 470 j located away from the curved section 460 j onto the first cover 100 j is located out of and substantially located next to the area C of the contact surface 110 of the first cover 100 j.

In the above embodiments, the extension sections are spaced apart from each other. However, the present disclosure is not limited thereto. Please refer to FIG. 15 , which is a plan view showing that a vapor chamber without a second cover according to a twelfth embodiment of the present disclosure. In this embodiment, the extension sections 470 k abut to each other.

Note that the distribution area of the second capillary structure 400 may greater than or equal to the distribution area of the first capillary structure 300 with the premise that the second capillary structure 400 has a capability of transmitting the cooling fluid stronger than that of the first capillary structure 300. That is, the present disclosure is not limited to that the orthogonal projection of the second capillary structure 400 onto the first cover 100 is smaller than that of the first capillary structure 300 onto the first cover 100 with the premise stated above. Herein, the capability of transmitting the cooling fluid is proportional to the degree of capillary action.

In addition, in the above embodiments, the first capillary structure 300 is stacked on the first cover 100. However, the present disclosure is not limited thereto. In some embodiments, the first capillary structure may be stacked on the second cover.

According to the vapor chamber discussed above, when the vapor chamber is placed vertically and the evaporation area is located higher than the condensation area, or when the evaporation area and the condensation area have a relative long distance inbetween, the condensed cooling fluid in the condensation area still can be transmitted back to the evaporation area with the help of the second capillary structure and the first capillary structure to complete the circulation.

The embodiments are chosen and described in order to best explain the principles of the present disclosure and its practical applications, to thereby enable others skilled in the art best utilize the present disclosure and various embodiments with various modifications as are suited to the particular use being contemplated. It is intended that the scope of the present disclosure is defined by the following claims and their equivalents. 

What is claimed is:
 1. A vapor chamber, configured to accommodate a cooling fluid, and the vapor chamber comprising: a first cover, having a contact surface, wherein the contact surface is configured to be in thermal contact with a heat source, and; a second cover, wherein the second cover and the first cover are attached to each other to form a chamber therebetween, and the chamber is configured to accommodate the cooling fluid; a first capillary structure, wherein the first capillary structure is located in the chamber and stacked on the first cover; a second capillary structure, wherein the second capillary structure is located in the chamber and stacked on the first capillary structure, the second capillary structure is different from the first capillary structure, and an entire projection of the second capillary structure onto the first cover is completely overlapped with a projection of the first capillary structure onto the first cover; a plurality of supporting posts, wherein each of the plurality of supporting posts is in direct contact with the first cover and the second cover at two opposite sides thereof; and first and second irregularly-shaped hollow parts, formed through the first cover and the second cover, wherein the contact surface is located between the first and second irregularly-shaped hollow parts, and the second capillary structure surrounds the first irregularly-shaped hollow part.
 2. The vapor chamber according to claim 1, wherein the chamber has an evaporation area and a condensation area, the evaporation area is wider than the condensation area, a side of the second capillary structure is located in the condensation area, another side of the second capillary structure extends towards the evaporation area, the contact surface corresponds to the evaporation area, and part of the projection of the second capillary structure onto the first cover is located in the contact surface of the first cover.
 3. The vapor chamber according to claim 2, wherein the second capillary structure is in a ring-shape.
 4. The vapor chamber according to claim 3, wherein the second capillary structure has a first curved section, a second curved section, two extension sections, and a bridge section, the first curved section and the second curved section are located opposite to each other, the first curved section is located in the condensation area, at least part of the second curved section is located in the evaporation area, a projection of the second curved section onto the first cover is located out of the contact surface of the first cover, the two extension sections are located opposite to each other, the two extension sections are respectively located between and connected to the first curved section and the second curved section, an end of the bridge section is connected to the second curved section, and a projection of another end of the bridge section onto the first cover is located in the contact surface of the first cover.
 5. The vapor chamber according to claim 2, wherein the second capillary structure is in a U-shape.
 6. The vapor chamber according to claim 5, wherein the second capillary structure has a curved section and two extension sections, the curved section is located in the condensation area, the two extension sections are located opposite to each other, the two extension sections are respectively connected to two opposite ends of the curved section and extend towards the evaporation area, and a projection of an end of each of the two extension sections located away from the curved section onto the first cover is located in the contact surface of the first cover.
 7. The vapor chamber according to claim 6, wherein the two extension sections abut to each other.
 8. The vapor chamber according to claim 6, wherein the two extension sections are spaced apart from each other.
 9. The vapor chamber according to claim 1, wherein the chamber has an evaporation area and a condensation area, the evaporation area is wider than the condensation area, a side of the second capillary structure is located in the condensation area, another side of the second capillary structure extends towards the evaporation area, the contact surface corresponds to the evaporation area, the projection of the second capillary structure onto the first cover is located out of and substantially located next to the contact surface of the first cover, and the second capillary structure is in a U-shape.
 10. The vapor chamber according to claim 9, wherein the second capillary structure has a curved section and two extension sections, the curved section is located in the condensation area, the two extension sections are located opposite to each other, the two extension sections are respectively connected to two opposite ends of the curved section and extend towards the evaporation area, and a projection of an end of each of the two extension sections located away from the curved section onto the first cover is located out of and substantially located next to the contact surface of the first cover.
 11. The vapor chamber according to claim 10, wherein the two extension sections abut to each other.
 12. The vapor chamber according to claim 10, wherein the two extension sections are spaced apart from each other.
 13. A vapor chamber, configured to accommodate a cooling fluid, and the vapor chamber comprising: a first cover, having a contact surface, wherein the contact surface is configured to be in thermal contact with a heat source, and; a second cover, wherein the second cover and the first cover are attached to each other to form a chamber therebetween, and the chamber is configured to accommodate the cooling fluid; a first capillary structure, wherein the first capillary structure is located in the chamber and stacked on the first cover; a second capillary structure, wherein the second capillary structure is located in the chamber and stacked on the first capillary structure, the second capillary structure has a capability of transmitting the cooling fluid greater than that of the first capillary structure, and an entire projection of the second capillary structure onto the first cover is completely overlapped with a projection of the first capillary structure onto the first cover; a plurality of supporting posts, wherein each of the plurality of supporting posts is in direct contact with the first cover and the second cover at two opposite sides thereof; and first and second irregularly-shaped hollow parts, formed through the first cover and the second cover, wherein the contact surface is located between the first and second irregularly-shaped hollow parts, and the second capillary structure surrounds the first irregularly-shaped hollow part.
 14. The vapor chamber according to claim 13, wherein the chamber has an evaporation area and a condensation area, the evaporation area is wider than the condensation area, a side of the second capillary structure is located in the condensation area, another side of the second capillary structure extends towards the evaporation area, the contact surface corresponds to the evaporation area, and part of an orthogonal projection of the second capillary structure onto the first cover is located in the contact surface of the first cover.
 15. The vapor chamber according to claim 14, wherein the second capillary structure is in a ring-shape.
 16. The vapor chamber according to claim 15, wherein the second capillary structure has a first curved section, a second curved section, two extension sections, and a bridge section, the first curved section and the second curved section are located opposite to each other, the first curved section is located in the condensation area, at least part of the second curved section is located in the evaporation area, an orthogonal projection of the second curved section onto the first cover is located out of the contact surface of the first cover, the two extension sections are located opposite to each other, the two extension sections are respectively located between and connected to the first curved section and the second curved section, an end of the bridge section is connected to the second curved section, and an orthogonal projection of another end of the bridge section onto the first cover is located in the contact surface of the first cover.
 17. The vapor chamber according to claim 14, wherein the second capillary structure is in a U-shape.
 18. The vapor chamber according to claim 17, wherein the second capillary structure has a curved section and two extension sections, the curved section is located in the condensation area, the two extension sections are located opposite to each other, the two extension sections are respectively connected to two opposite ends of the curved section and extend towards the evaporation area, and an orthogonal projection of an end of each of the two extension sections located away from the curved section on the first cover is located in the contact surface of the first cover.
 19. The vapor chamber according to claim 18, wherein the two extension sections abut to each other.
 20. The vapor chamber according to claim 18, wherein the two extension sections are spaced apart from each other.
 21. The vapor chamber according to claim 13, wherein the chamber has an evaporation area and a condensation area, the evaporation area is wider than the condensation area, a side of the second capillary structure is located in the condensation area, another side of the second capillary structure extends towards the evaporation area, the contact surface corresponds to the evaporation area, an orthogonal projection of the second capillary structure onto the first cover is located out of and substantially located next to the contact surface of the first cover, and the second capillary structure is in a U-shape.
 22. The vapor chamber according to claim 21, wherein the second capillary structure has a curved section and two extension sections, the curved section is located in the condensation area, the two extension sections are located opposite to each other, the two extension sections are respectively connected to two opposite ends of the curved section and extend towards the evaporation area, and an orthogonal projection of an end of each of the two extension sections located away from the curved section onto the first cover is located out of and substantially located next to the contact surface of the first cover.
 23. The vapor chamber according to claim 22, wherein the two extension sections abut to each other.
 24. The vapor chamber according to claim 22, wherein the two extension sections are spaced apart from each other. 